Display screen or portion thereof with transitional graphical user interface



FIG. 1 is the first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design;

FIG. 2 is the second image thereof;

FIG. 3 is the third image thereof;

FIG. 4 is the fourth image thereof;

FIG. 5 is the fifth image thereof;

FIG. 6 is the sixth image thereof;

FIG. 7 is the seventh image thereof;

FIG. 8 is the eighth image thereof;

FIG. 9 is the ninth image thereof; and,

FIG. 10 is the tenth image thereof.

The outermost broken line showing of the display screen and all other broken lines showing portions of the graphical user interface are included for the purpose of illustrating portions of the article and form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 